The purpose of the National Cancer Institute (NCI) Surveillance Epidemiology and End Results (SEER) Program is to assemble and report annual estimates of cancer statistics that pertain to incidence, prevalence, and patient survival; monitor trends to identify important changes in cancer rates for population subgroups defined by geographic, demographic, and social characteristics; provide information on changes over time in stage of disease at diagnosis and types of therapy, as well as associated changes in cancer patient survival; carry out special studies that provide insight into trends in cancer rates, treatment patterns, and other relevant aspects of cancer control; and provide an infrastructure to support cancer research through its data.